What could cause me to test positive for methamphetamine and amphetamine on a urine drug test that was confirmed using gc-ms when i do not use drugs?

What DO you take?: Someone else's specimen may have been mislabeled as yours. Or, you may be taking a medication that is "cross-reactive" with amphetamines and caused a false-positive result. Labs usually include such cautionary information in their reports. Go over the lab report and your meds with the ordering physician.

Hard to say: If the test were not done with "chain of custody," where there are sealed containers with signature forms where everybody who handles the specimen, from start to finish, certifies that it is YOUR specimen, then there is the small possibility of lab error. Lab errors of this kind occur in a very tiny percentage of cases, such as 0.05%, but that means if a lab does 10k specs there could be 5 errors